Tooth decay is the destruction of your tooth enamel, the hard, outer layer of your teeth. It can be a problem for children, teens and adults. Plaque, a sticky film of bacteria, constantly forms on your teeth. When you eat or drink foods containing sugars, the bacteria in plaque produce acids that attack tooth enamel. The stickiness of the plaque keeps these acids in contact with your teeth and over time the enamel can break down. This is when cavities can form.
TCavities are more common among children, but changes that occur with aging make cavities an adult problem, too. Recession of the gums away from the teeth, combined with an increased incidence of gum disease, can expose tooth roots to plaque. Tooth roots are covered with cementum, a softer tissue than enamel. They are susceptible to decay and are more sensitive to touch and to hot and cold. It's common for people over age 50 to have tooth-root decay.
TDecay around the edges, or a margin, of fillings is also common for older adults. Because many older adults lacked benefits of fluoride and modern preventive dental care when they were growing up, they often have a number of dental fillings. Over the years, these fillings may weaken and tend to fracture and leak around the edges. Bacteria accumulate in these tiny crevices causing acid to build up which leads to decay the during infancy. They are usually lost and replaced by permanent teeth, but in the absence of permanent replacements, they can remain functional for many years.